Adds `//tag::notable-breaking-changes[]` to several breaking changes
files. This tag is required for reuse in the [Elastic Stack Installation
and Upgrade Guide][0].
Also replaces a relative xref with an external links. External links are
required for reuse in the Installation and Upgrade Guide.
[0]: https://www.elastic.co/guide/en/elastic-stack/master/index.html
This commit finalizes the work done to rename size to max_docs in
reindex and update/delete by query. size is no longer supported in URL
or outer level body for the 3 APIs (though size in update/delete-by-query
will and has always been interpreted as scroll_size, it is not to be relied
upon).
Continuation of #41894Closes#24344
Removed the leniency when encoding remote reindex search requests that
was introduced in 7.x. All index-names are now encoded before being sent
to the remote host.
Follow-up to #40303